The present invention relates to a process for preparing ethylenediamine (EDA), where the process comprises the steps a) to c). In step a), formaldehyde is reacted with hydrocyanic acid (HCN) to form formaldehyde cyanohydrin (FACH), where the hydrocyanic acid is completely free or largely free of sulfur dioxide (SO.sub.2). The FACH prepared in this way is reacted with ammonia (NH.sub.3) to form aminoacetonitrile (AAN) in step b), whereupon a hydrogenation of AAN in the presence of a catalyst to form EDA is carried out in step c).

The present invention pertains to a process for preparing 3-hydroxy-3-methylbutyric acid (HMB) or a salt thereof, the method comprising (a) reacting isobutylene oxide with cyanide in order to obtain 3-hydroxy-3-methylbutyronitrile, and (b) hydrolyzing the 3-hydroxy-3-methylbutyronitrile obtained in step (a) in order to obtain HMB, wherein hydrolysis step (b) is performed using either at least one nitrilase enzyme or, alternatively, using a combination of enzymes, said combination comprising at least one nitrile hydratase and at least one amidase.

The present invention pertains to a process for preparing 3-hydroxy-3-methylbutyric acid (HMB) or a salt thereof, the method comprising (a) reacting isobutylene oxide with cyanide in order to obtain 3-hydroxy-3-methylbutyronitrile, and (b) hydrolyzing the 3-hydroxy-3-methylbutyronitrile obtained in step (a) in order to obtain HMB, wherein hydrolysis step (b) is performed using either at least one nitrilase enzyme or, alternatively, using a combination of enzymes, said combination comprising at least one nitrile hydratase and at least one amidase.

A process for purifying ethylene cyanohydrin involves incubating an industrial grade ethylene cyanohydrin product with at least one titanium(IV)alkoxide. Ethylene cyanohydrin products with purities of >99% contain less than 0.05% of ethylene glycol (EG), and/or contain a water content of less than 1000 ppm.

A process for purifying ethylene cyanohydrin involves incubating an industrial grade ethylene cyanohydrin product with at least one titanium(IV)alkoxide. Ethylene cyanohydrin products with purities of >99% contain less than 0.05% of ethylene glycol (EG), and/or contain a water content of less than 1000 ppm.

A process purifies ethylene cyanohydrin by incubating an industrial grade ethylene cyanohydrin product with at least one titanium(IV)alkoxide. Ethylene cyanohydrin products have purities >99% and have less than 0.05% of ethylene glycol (EG), and/or have a water content of less than 1000 ppm.

A process purifies ethylene cyanohydrin by incubating an industrial grade ethylene cyanohydrin product with at least one titanium(IV)alkoxide. Ethylene cyanohydrin products have purities >99% and have less than 0.05% of ethylene glycol (EG), and/or have a water content of less than 1000 ppm.

A process purifies ethylene cyanohydrin by incubating an industrial grade ethylene cyanohydrin product with at least one titanium(IV)alkoxide. Ethylene cyanohydrin products have purities >99% and have less than 0.05% of ethylene glycol (EG), and/or have a water content of less than 1000 ppm.